There exist in today's market devices, such as document scanners, which serve applications for which it is desirable to illuminate the scanned object, typically a document, with substantially uniform illumination. The scanned documents, for example ID cards, drivers' license, business cards and the like, are typically analyzed to extract information from the scanned document and non-uniform illumination degrades the ability to extract the desired information.
A variety of devices for detecting the presence of a document to be scanned exists, in particular for flat bed scanner, having a lid. One method is measuring the distance traveled by a light beam, thereby determining if the beam is returned from the lid or a document placed on the transparent surface. In other methods a switch is activated, when the lid is closed, whereby the scanning operation begins.
Typically, in portable scanning/image acquisition apparatuses, the transparent surface on which the document to be scanned is placed is in a generally upright or inclined orientation, whereby the tangible document is supported by a supporting element to prevent the document from sliding down due to the force of gravity. Such scanners/image acquisition apparatuses do not include a lid.
One such portable image acquisition apparatus is provided by Iuval Hatzav et al in US application 20080285094 ('094), the disclosure of which is included herein by reference. Referring to FIG. 1 (Prior art), an image acquisition apparatus 20 operable by pressing on button 26, as provided by '094, is shown. A document 10 is place adjacent to a substantially transparent window, having an external surface 24, and is supported by supporting structure 22. The imaging operation of document 10 commences when button 26 is depressed. A camera (not shown), disposed inside the internal space of housing 28, acquires an image of document 10, the image being associated with tangible document 10.
One method to sense the presence of a document 10 on external surface 24, to automatically start the imaging operation, is by pacing a laser diode coupled with a photodiode inside internal space of housing 28. The laser is directed towards the transparent window. When transparent surface 24 is exposed, a substantial portion of the light passes through the transparent window and does not return to be sensed by the photodiode. When transparent surface 24 is exposed, a substantial portion of the light passes through the transparent window and does not return to be sensed by the photodiode. When a document 10 is positioned on external surface 24, a substantial portion of the light is reflected back by document 10 and sensed by the photodiode, whereby commencing the imaging operation. In this method, the laser beam may endanger bodies positioned in the path of the laser beam.
Thus, there is a need for and it would be advantageous to have an image apparatus that is activated by placing a document to be imaged on a substantially transparent window surface of the apparatus.